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        2019-09-28 09:27:52   來源:湖南成考網    點擊: 學習交流群+ 加入 微信公眾號+ 關注
          122. It is hard to track the blue whale, the ocean’s largest creature, which has almost been killed off by commercial whaling and is now listed as an endangered species. Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior. So biologists were delighted early this year when, with the help of the Navy, they were able to track a particular blue whale for 43 days, monitoring its sounds. This was possible because of the Navy’s formerly top-secret system of underwater listening devices spanning the oceans. Tracking whales is but one example of all exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies. Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption for the first time and that they plan similar studies. Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures. The speed of sound in water is roughly one mile a second, slower than through land but faster than through air. What is most important, different layers of ocean water can act as channels for sounds, focusing them in the same way a stethoscope (聽診器) does when it carries faint noises from a patient’s chest to a doctor’s ear. This focusing is the main reason that even relatively weak sounds in the ocean, especially low-frequency ones, can often travel thousands of miles. [共5題]

          (1) The passage is chiefly about ________.

          (A) an effort to protect an endangered marine species

          (B) the exposure of a US Navy top-secret weapon

          (C) the civilian use of a military detection system

          (D) a new way to look into the behavior of blue whales


          (2) The underwater listening system was originally designed ________.

          (A) to monitor deep-sea volcanic eruptions

          (B) to replace the global radio communications network

          (C) to study the movement of ocean currents

          (D) to trace and locate enemy vessels


          (3) The deep-sea listening system makes use of ________.

          (A) the unique property of layers of ocean water in transmitting sound

          (B) the capability of sound to travel at hligh speed

          (C) low-frequency sounds travelling across different layers of water

          (D) the sophisticated technology of focusing sounds under water


          (4) It can be inferred from the passage that ________.

          (A) blue whales are no longer endangered with the use of the new listening system

          (B) new radio devices should be developed for tracking the endangered blue whales

          (C) military technology has great potential in civilian use

          (D) opinions differ as to whether civilian scientists should be allowed to use military technology


          (5) Which of the following is true about the US Navy underwater listening network?

          (A) It has been replaced by a more advanced system.

          (B) It is now partly accessible to civilian scientists.

          (C) It became useless to the military after the cold war.

          (D) It is indispensable in protecting endangered species.






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